1. Field of the Invention
This invention relates to a magnetic recording tape cassette.
2. Description of the Prior Art
Conventionally, a magnetic recording tape cassette of the type having a pair of take-up hubs generally has a structure as shown in FIG. 3. In FIG. 3, reference numeral 1 denotes a casing of the cassette, and the casing 1 is provided, on one side thereof, with an access opening through which the magnetic recording tape accommodated in the casing 1 is drawn out for recording or reproduction by a magnetic recording and reproducing system such as a tape recorder. The access opening is closed by a lid member 2 while not in use. The lid member 2 is mounted for rotation on the casing 1 by pivots 3 which inwardly project from arms 2a integrally formed on opposite sides of the lid member 2 and are received for rotation in holes 4 formed in opposed sides of the casing 1 perpendicular to the side in which the access opening is formed as shown in FIGS. 4 and 5. At least one of the pivots 3 is provided with a slit 3a extending along the longitudinal axis in order to facilitate assembly. Each of the holes 4 has a square cross section each side of which has a length substantially equal to the outer diameter of the pivot 3, and the lid member 2 is urged upward by a spring (not shown).
However, the conventional magnetic recording disk cassette is disadvantageous on the following points. As shown in FIG. 5, the dimension l.sub.2 of the pivot 3 as measured along the slit 3a is smaller than the outer diameter l.sub.1 of the pivot 3, and accordingly, if the length of each side of the hole 4 in which the pivot 3 is to be received is selected to be equal to the outer diameter l.sub.1 of the pivot 3, a space A having a width substantially equal to l.sub.1 -l.sub.2 is formed between the lower surface of the pivot 3 and the lower side of the hole 4 since the lid member 2 is spring-urged upward, whereby a large space is formed between the lower surface of the arm 2a of the lid member 2 and the upper surface of the casing 1 to adversely affect the external appearance of the cassette. Further, for a similar reason, the lid member 2 is movable back and forth with respect to the casing 1 when the lid member 2 is opened, which is not preferred.